Transcript BiologyReferences_files/Evolution 2012 with study guide

Evolution
A process of change through time
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Evolution
• -is the change in the inherited traits of a
population of organisms through successive
generations. This change results from
interactions between processes that introduce
variation into a population, and other processes
that remove it. As a result, variants with
particular traits become more, or less, common.
A trait is a particular characteristic—anatomical,
biochemical or behavioral—that is the result of
gene–environment interaction.
• Or……. Descent with modification
Evolution
• Definition: the change in genetic
composition of a population of organisms
over time
• Microevolution: change in a population’s
Frequency of alleles
Macroevolution: multiplication of new
species
=Diversity
Charles Darwin
Aboard the HMS Beagle
December 1831 to
October 1836
First Scientist to study
evolution on the
Galapagos Islands
On the Origin of Species, published on 24 November 1859
Evolution occurs because
of Natural Selection, with
nature acting as the
selecting agent.
Organisms better adapted
to the environment survive
and reproduce more
successfully than less-well
adapted organisms.
http://anthro.palomar.edu/evolve/evolve_2.htm
Theories of Evolution
Jeane Babtiste Lamark
The Principle of Use and Disuse:
New structures developed in an
organism during the course of
evolution because they were
needed and unused structures
were lost.
Inheritance of Acquired
Characteristics: Characteristics
During a lifetime were passed
onto offspring.
Thomas Malthus (1766-1834)
Population growth not always desirable
Population increases geometrically; food supply
increases arithmetically
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Sir Charles Lyell (1797-1875)
Geologist
The earth was much older than
originally thought – Time is essential
Natural Selection
• Populations change in response to their
environment.
• Acts on phenotype of an organism.
(Not genotype)
• Theory of evolution by natural
selection
– Proposed by both Darwin and Alfred
Wallace
– Based on four observations
• Genetic variation exists among individuals
• Reproductive ability of species causes its
populations to geometrically increase
• Organisms compete for resources
• Offspring with most favorable
characteristics is most likely to survive
Speciation
• Formation of a new
species
What’s a species?
• A population whose members may breed
and produce fertile offspring …
• No not a liger!
Nor a mule!
Adaptations(Evolutionary)
• Inherited characteristics that
enables a species to survive
and reproduce
• EX: Darwin’s finches…
• Inheritable: variation in
genetics:
Mutations, recombination
of genes, random
movement of chromosomes
during meiosis
Reproductive Isolation
Separation of two groups over a long period of time may
Result in change in the genetic makeup of the two groups
Making them unable to reproduce with each other.
Geographic Isolation
A body of water or mountain range separates a population of a species
resulting in evolution of new species.
– Artificial selection
• Breeders developing many varieties of
domesticated animals in a few generations
• Plant varieties, such as kale and broccoli,
developed from wild cabbage
Artificial
selection in
Brassica
oleracea
Mustard Evidence
http://evolution.berkeley.edu/evolibrary/home.php
EVIDENCE OF EVOLUTION
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Geological Record:
Through radioactive dating the
oldest rocks in the earth’s crust, the age of the earth is
4.5 – 5 billion years old.
Fossils:
Traces of once living organisms
In Rock
In Amber
Petrifaction 
In Ice
Comparative Anatomy: Organism with similar body
Structure evolved along the same line.
Homologous Structures: Evidence of common ancestry.
Analogous
Structures :
Same function,
structurally
different.
Show no common
ancestry.
Vestigial Structures:
Structures in an organism through
evolution have been lost or reduced in size because they were
no longer necessary trait for survival.
Embryology
http://evolution.berkeley.edu/evolibrary/home.php
Bacterial Antibiotic Resistance
Modern Theories of Evolution
A change in the DNA of an organism over a period of time
Sources of variation
Sexual Reproduction: A recombination of alleles.
Random and spontaneous gene and chromosome mutations.
Natural Selection is one of the basic mechanisms of
evolution, along with mutation, migration, and
genetic drift. Darwin's grand idea of evolution by
natural selection is relatively simple but often
misunderstood.
To find out how it works, imagine a population of
beetles:
There is variation in traits.
For example, some beetles are green and some are
brown.
There is differential reproduction.
Since the environment can't support unlimited population
growth, not all individuals get to reproduce to their full
potential. In this example, green beetles tend to get eaten by
birds and survive to reproduce less often than brown beetles
do.
There is heredity.
The surviving brown beetles have brown baby beetles
because this trait has a genetic basis.
End result:
The more advantageous trait, brown coloration, which
allows the beetle to have more offspring, becomes more
common in the population. If this process continues,
eventually, all individuals in the population will be brown.
If you have variation, differential reproduction, and heredity,
you will have evolution by natural selection as an outcome. It
is as simple as that.
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Testing the Evolutionary Hypothesis
of Common Ancestry
Chromosome numbers in
the great apes:
human (Homo)
chimpanzee (Pan)
gorilla (Gorilla)
orangutan (Pogo)
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Testing the Evolutionary Hypothesis
of Common Ancestry
Testable prediction: If these
organisms share common ancestry, the
human genome must contain a fused
chromosome.
Ancestral
Chromosomes
Chromosome numbers in
the great apes
(Hominidae):
human (Homo)
chimpanzee (Pan)
gorilla (Gorilla)
orangutan (Pogo)
Fusion
Homo sapiens
Centromere #1
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Telomere
sequences
Centromere #2
Centromere
Telomere
Testable prediction: The marks of that fusion
must appear in one of the human
chromosomes.
Human Chromosome #2 shows the exact point
at which this fusion took place
Homo sapiens
centromere
#13 (inactive)
Telomere
sequences
centromere
#12 (active)
Hillier et al (2005) “Generation and Annotation of the DNA
sequences of human chromosomes 2 and 4,” Nature 434: 724-731.
Fossils show life
Started….
As bacteria and
archae
Then invertebrates
Then vertebrates:
Fish, amphibians,
Reptiles, birds and
Mammals…….
“There is grandeur in this view of
life; with its several powers having
been originally breathed into a few
forms or into one; and that, whilst
this planet has gone cycling on
according to the fixed law of
gravity, from so simple a beginning
endless forms most wonderful and
most beautiful have been, and are
being evolved.”
Topical Generalization # 1
Evolution is the result of natural selection.
•Guiding QuestionsWhat are selective forces?Why is natural selection the mechanism
for evolution?What is an adaptation?How do behavioral, physiological, and structural
adaptations differ? In terms of evolution, can an individual organism adapt?What
defines a species?How do selective forces guide evolution?What is genetic fitness?
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Topical Generalization # 2
Variation within populations can arise
through different processes.
Essential/Guiding QuestionsWhat built in mechanisms do organisms have to ensure variation occurs?What are sources of
variation?What is a mutation?What is a mutagen?Are mutations always bad?
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Topical Generalization #3
There is scientific evidence to support
evolution.
Guiding QuestionsWhat evidence do scientists use to support the theory of evolution?How has evidence for evolution changed as
technology has changed?Who are the initial key contributors to the theory of evolution? Why can’t pieces of evidence be used
individually to support evolution?
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Evolution Vocabulary
Also go to Quizlet activity
Charles Darwin
Jean Baptiste Lamarck
Thomas Malthus
Charles Lyell
Galapagos Islands
macroevolution
microevolution
fossil
embryology
homologous
vestigial
analogous structures
molecular evidence
phylogenetic trees
selective forces
adaptation
behavioral adaptation
physiological adaptation
structural adaptation
genetic fitness
species
genetic fitness
extinction
natural selection
mutation
mutagens
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